Though growing waterlilies from seed will not produce exact
duplicates of the parents (except with some species lilies),
it can be fun! For how to actually create your own new hybrids,
see the following articles. Though these articles are about tropical
waterlilies, the information applies to hardies as well.

Whether
you have made a cross yourself or found a ripening pod made by
the bees, you will want to bag it. Plastic bags either zipped
or twist-tied loosely around the stem work well as do old panty
hose. When the pod ruptures, seeds, each of which will be surrounded
by a little floatation aril, will float up into the bag trying
to reach the surface of the water.

When the bag is collected, the contents can be placed in a
small bucket or other open container with plenty of water. Small
white, tan and red seeds will not be viable. Larger dark seeds,
gray, green and black are those that can be viable. Within a
few days, arils and residual flower parts will rot away and viable
seeds will sink to the bottom. Swirling water in the bucket and
pouring debris off several times will leave just the seeds.

At this point, tropical seeds can be dried, on paper towels
for instance, and stored indefinitely in the refrigerator or
they can be planted. Seeds from all hardies (Nymphaea),
N. gigantea from the Australian subgenus Anecphya,
as with Victoria and Euryale, must be stored in
water to remain viable.

Though seeds can be sprouted in warm water and potted individually,
we prefer to plant them before they sprout. The number of seeds
determines container size, everything from small pots to dish
pans to small ponds. We put a layer of soil in the bottom, add
water to the brim, level and compact the soil once it has settled
from filling with water. We then distribute the seeds as evenly
as possible over the soil and drizzle a thin layer of white sand
through the water over the seeds. This helps to anchor them and
to see them as they sprout. Adding water after putting the seeds
are put in can dislodge them, as can placing the container in
a pond.

When seedlings have made several floating leaves in smaller
containers, we carefully dig them up and pot them individually.
In small ponds designed for seedlings we let plants grow to blooming
stage and then remove them, either to propagate or discard, making
more space for still developing seedlings.

Craig Presnell prefers to pot seeds individually. In his experience,
pods that make only a few seeds often have the most promising
offspring and he doesn't want to risk losing any in group planting.